Full changelog:
- Bugfix: make-release: Add README.GPU document
- Demote USB string fetch failure to LOG_DEBUG since it is rather common
- Bugfix: RPC: devscan shouldn't be available to read-only access
- Bugfix: bigpic: Ignore the bitfury chip's counter as best we can
- Bugfix: bigpic: Accept other delimiters in Bitfury BF1 product string in autodetection
- Bugfix: Fix VCOM/fpgautils build check
- Bugfix: Only include VCOM code when VCOM/fpgautils support is being built
- Bugfix: Reimplement scan-serial "all" keyword
- Bugfix: bitforce detect: Close device after ZGX failure
- Bugfix: Define lowl_usb even if libusb support is omitted, since VCOM and
HID drivers check against it for warnings